I had a spot in the floor in the engine room that had some wet balsa coring. I cut the top layer of glass away and removed wet coring. I went out about another 6” to make sure I got all of the wet stuff removed. The wet area traveled under one of the stringers in about a 12” area and partially under the outboard stringer. I was thinking of replacing the coring with marine plywood and using cabosil mixed with epoxy resin to fill any gaps between the new coring and the bottom of the stringers. Does that sound like a good plan? Thanks

One more question. The coring that goes up underneath the transom was soft and I cleaned that out so it’s open under there now. Could I just fill that area with cabosil instead of putting coring back in? It would essentially be an area of about 3/4” tall by 1 1/2” deep. Is that asking too much of cabosil?

Boat year, make and model. Picures for sure need to be included.
The BIG question to start is, how did you find the wet balsa/ what led you to it.
A little more info and pictures will help get your answers.

More info will help you to get the best advise.
How familiar are with resins?
Putting that much thickened resin in at once can cause problems unless you know what you are doing